This invention relates to apparatus for cleaning the interior of tubes, and more specifically to tube cleaning apparatus having swingable cutter arms.
Over a period of time, the insides of fluid conducting tubes develop scale, rust, or other deposits. Accordingly, the interiors of the tubes must be periodically cleaned. Often this is done by utilizing an apparatus having a body that can be secured to a rotatable drive shaft; a plurality of cutter arms, which are pivotally connected to the body for movement between a retracted position and an extended position; and a plurality of cutter heads, with one cutter head secured to each cutter arm. To clean a tube, the apparatus is inserted into the tube and rotated by the drive shaft. When rotated, the cutter arms, acting under the influence of centrifugal force, move radially outward to the extended position, and the cutter heads come into engagement with the interior of the tube. Further rotation scrapes the cutter heads across the inside surface of the tube, dislodging deposits from that surface. Typical prior art devices are disclosed in U.S. Pat. Nos. 928,432; 1,472,255; and 2,079,190. These references, along with U.S. Pat. No. 3,525,111 which is discussed below, appear to be the prior art known to applicant which is most relevant to the present disclosure.
With the prior art devices, it is often difficult to guide the cleaning apparatus into a tube because the cutter arms, being pivotally connected to the body, may swing outward as the apparatus is moved toward the tube. The cutter arms may strike the rim of the tube, preventing or at least hampering entry of the cleaning apparatus into the interior of the tube. This difficulty is compounded by the fact that occasionally the apparatus is rotated before it is inside the tube, further tending to swing the cutter arms to an outward position. Commonly, a considerable amount of attention and time, often involving expensive manual labor, must be taken to carefully insert the cutter arms into the tube.
In accordance with the present invention, means are provided to urge the cutter arms together to the retracted position. As the apparatus is inserted into a tube, the cutter arms are restricted from swinging outward, substantially facilitating entry of the cleaning apparatus into the tube. With the present invention, less time, skill, attention and expensive manual labor is needed to guide the apparatus into the tube.
Means for urging arms in a specific direction, wherein the arms are pivotally connected to a body which is rotated while moved through a tube, are disclosed in the last of the four above-cited references, U.S. Pat. No. 3,525,111. The apparatus shown in this patent, however, urges the arms outward to an extended position for maintaining contact between the arms and the interior of the tube. Thus, both the specific purpose--outwardly urging the arms--and the general purpose--maintaining contact between the arms and the interior surface of the tube--of the device disclosed in this latter patent are the opposite of those of the present invention. It is contended, hence, that this reference does not disclose or suggest means for urging cutter arms of a rotatable tube cleaning device together to a retracted position.